An Orbit Fit for the Grillmair Dionatos Cold Stellar Stream

Journal Article · Thu Jan 01 04:00:00 EST 2009 · Submitted to Astrophys.J.

DOI:https://doi.org/10.1088/0004-637X/697/1/207· OSTI ID:951125

Willett, Benjamin A; Newberg, Heidi Jo; Zhang, Haotong; Yanny, Brian; Beers, Timothy C

We use velocity and metallicity information from Sloan Digital Sky Survey and Sloan Extension for Galactic Understanding and Exploration stellar spectroscopy to fit an orbit to the narrow 63{sup o} stellar stream of Grillmair and Dionatos. The stars in the stream have a retrograde orbit with eccentricity e = 0.33 (perigalacticon of 14.4 kpc and apogalacticon of 28.7 kpc) and inclination approximately i {approx} 35{sup o}. In the region of the orbit which is detected, it has a distance of about 7-11 kpc from the Sun. Assuming a standard disk plus bulge and logarithmic halo potential for the Milky Way stars plus dark matter, the stream stars are moving with a large space velocity of approximately 276 km s{sup -1} at perigalacticon. Using this stream alone, we are unable to determine if the dark matter halo is oblate or prolate. The metallicity of the stream is [Fe/H] = -2.1 {+-} 0.1. Observed proper motions for individual stream members above the main sequence turnoff are consistent with the derived orbit. None of the known globular clusters in the Milky Way have positions, radial velocities, and metallicities that are consistent with being the progenitor of the GD-1 stream.

• Research Organization: Fermi National Accelerator Laboratory (FNAL), Batavia, IL
• Sponsoring Organization: USDOE
• DOE Contract Number: AC02-07CH11359
• OSTI ID: 951125
• Report Number(s): FERMILAB-PUB-09-104-A-CD; arXiv eprint number arXiv:0901.4046
• Journal Information: Submitted to Astrophys.J., Journal Name: Submitted to Astrophys.J.
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
Astrophysics
EXPLORATION
INCLINATION
MILKY WAY
NONLUMINOUS MATTER
PROPER MOTION
SKY
SPECTROSCOPY
STARS
SUN
VELOCITY